Isolated luciferases and the use thereof

ABSTRACT

The invention relates to the nucleotide and amino acid sequences, and to the activity and use, of the luciferases LuAL, Lu164, Lu16, Lu39, Lu45, Lu52 and Lu22.

[0001] The invention relates to the nucleotide and amino acid sequences, and to the activity and use, of the luciferases LuAL, Lu164, Lu16, Lu39, Lu45, Lu52 and Lu22.

[0002] Luciferases

[0003] Luminescence is the term given to the emission of photons in the visible spectral range, with this emission being brought about by excitated emitter molecules. In contrast to fluorescence, the energy for this is not supplied externally in the form of radiation of shorter wavelength.

[0004] A distinction is made between chemiluminescence and bioluminescence. Chemoluminescence is the term given to a chemical reaction which leads to an excited molecule which itself emits light when the excited electrons return to the normal energy level. Bioluminescence is the term used when this reaction is catalyzed by an enzyme. The enzymes which participate in the reaction are generally termed luciferases.

[0005] A review of luminescent organisms can be found in Hastings et al. 1995.

[0006] Luciferases are peroxidases or monooxygenases and dioxygenases. The enzyme substrates, which form the starting substances for the light-emitting products, are termed luciferins. They differ from species to species. The quantum yield of the systems lies between 0.1 and 0.9 photons per transformed substrate molecule (Idelgaufts, 1993).

[0007] Luciferases can be classified on the basis of their origin or their enzymic properties. An overview of some luciferase types is given below:

[0008] Bacterial Luciferase TABLE 1 Bacterial luciferases Gene References/ product Organism Substrate λ Expression Patents Lux Vibrio fischerii FMN, 495 nm cytosolic Apley et al., 1985 Genes Dodecanal, Gustafson G., NADH U.S. Pat. No. 5196524

[0009] Coelenterazine-Dependent Eukaryotic Luciferases TABLE 2 Coelenterazine-dependent eukaryotic luciferases Gene References/ product Organism Substrate λ Expression Patents Renilla Renilla Coelenterazine 480 nm cytosolic Mathews et al., 1977 Luciferase reniformis Lorenz et al, 1991 Lorenz et al. 1996 Alan, P; WO 0020619 Milton J., U.S. Pat. No. 5418155 Roelant C., WO 9938999 Vargula/ Vargula Vargula 460 nm secretory Thomspon et al., 1989 Cypridia hilgendorferii Luciferin Thompson et al., 1990 Luciferase Tora, JP 05064583 Tora, JP 08027200 Renard et al., WO 9520653 Watasemia Watasenia Watasemia ? cytosolic Inoue et al., 1976 Luciferase scintillans Luciferin Olophorus Olophorus Coelenterazine 454 secretion Inouye et al, 2000 Luciferase gracilirostris Aequorin Aequoria Coelenterazine 470 nm cytosolic Head et al. 2000 aequoria (Ca²⁺ activated) Shimomura et al., 2000 Jones et al., 1999 Kendall et al., 1998 Inouye et al., 1985 Shimomura et al., 1969 Cormier et al., U.S. Pat. No. 5798441 Cormier et al., U.S. Pat. No. 5422266 Obelin Obelia Coelenterazine 470 nm cytosolic Matveev et al., 1999 Berestovskaya, 1999

[0010] Coelenterazine-Independent Eukaryotic Luciferase TABLE 3 Coelenterazine-independent eukaryotic luciferases Gene product Organism Substrate λ Expression References Firefly Photinus Firefly 550 nm cytosolic Webster et al., 1980 Luciferase pyralis Luciferin, Gould et al., 1988 ATP Sala-Newby et al, 1992 Bonin et al., 1994 Sherf B., U.S. Pat. No. 5670356 KIKK, JP 09187281

[0011] Luciferases can also be distinguished from each other on the basis of their substrate specificity. The most important substrates include coelenterazine (Jones et al., 1999) and luciferin, and also derivatives of the two substances. Diagrams of the substrates, and their transformation by luciferase, are shown below:

[0012] Luciferase Substrates

[0013] Some luciferase substrates, and their transformation, are depicted below by way of example. All the substrates which are shown here are transformed enzymically with the release of light and carbon dioxide (CO₂) and consumption of oxygen (O₂). The dependence of the reaction on cofactors or energy carriers (e.g. ATP in the case of Firefly Luciferase) is enzyme-specific.

[0014] Transformation of coelenterazine into coelenteramide by aequorin with the emission of light of wavelength 470 nm.

[0015] Transformation of luciferin into oxyluciferin by Firefly Luciferase with the emission of light of wavelength 560 nm.

[0016] Transformation of Vargula Luciferin into Vargula Oxyluciferin by Vargula Luciferase with the emission of light of wavelength 460 nm.

[0017] Reporter Systems

[0018] A reporter gene or indicator gene is the term which is generally given to genes whose gene products can readily be detected using simple biochemical or histochemical methods. At least 2 types of reporter gene are distinguished.

[0019] 1. Resistance genes. Resistance genes is the term given to genes whose expression confers on a cell resistance to antibiotics or other substances whose presence in the growth medium leads to cell death when the resistance gene is absent.

[0020] 2. Reporter gene. In recombinant DNA technology, the products of reporter genes are used as fused or unfused indicators. The most common reporter genes include beta-galactosidase (Alam et al., 1990), alkaline phosphatase (Yang et al., 1997; Cullen et al., 1992), luciferases and other photoproteins (Shinomura, 1985; Phillips G N, 1997; Snowdowne et al., 1984).

[0021] Classification of the Species Metridia longa

[0022]Arthropoda→→Crustacea→→Copepoda

[0023] The species Metridia longa belongs to the crustacea, especially the copepoda or zooplancton.

[0024] Isolating the cDNA

[0025] In order to investigate the bioluminescence activity of the species Metridia longa, specimens were caught in the White Sea (Kartesh Biological Station, Russia) and stored in liquid nitrogen. In order to prepare cDNA libraries of Metridia longa, the RNA was isolated by the method of Krieg (Krieg et al., 1996) using isothiocyanate. RT-PCR was carried out in order to prepare the cDNA. For this, 10 μg of RNA were incubated with reverse transcriptase (Superscript Gold II) in accordance with the following scheme: PCR 1. 30 seconds 95° C. 2.  6 minutes 68° C. 3. 10 seconds 95° C. 4.  6 minutes 68° C.

[0026] In order to inactivate the polymerase, the reaction products were incubated with proteinase K at 37° C. for 30 minutes, and the cDNA was precipitated with ethanol. The cDNA was dissolved in water and incubated at 37° C. for one hour with SfiI. The reaction products were subjected to gel filtration in order to separate off small fragments. The fractionated cDNA was then ligated into the SfiI-cut and dephosphorylated λTriplEx2 vector. In order to prepare a λ phage expression library, the cloned cDNA fragments were subsequently packaged into λ phages using the SMART cDNA Library Construction Kit (Clontech) in-vitro packaging system.

[0027] The recombinant phages which contained a cDNA insertion with potential for expressing coelenterazine-dependent luciferases were identified by carrying out a library screening.

[0028] For this, bacterial lawns composed of E. coli XL1-Blue were plated out on 90 mm culture dishes and incubated at 37° C. for 10 hours. They were then infected with 2500 phages per culture dish, with this then being followed by an incubation phase of 8 hours at 37° C. to enable plaques to be formed. The culture dishes were subsequently stored at 4° C. for one hour in order to harden the soft agar.

[0029] In order to carry out a replica plating, nitrocellulose membranes were saturated with E. coli XL1-Blue suspensions and dried. The dry membranes were laid for 60 seconds on the phage plaques and then laid on fresh agar plates. The agar plates were then incubated at 37° C. for 2 hours and 4 ml of SOB medium (+10 mM MgSO4, 0.2% maltose) were added. The bacterial lawn was detached, resuspended in LB medium (+20 mM IPTG) and incubated at 37° C. for one hour. The bacteria were harvested by centrifugation and disrupted by ultrasonication, and the bioluminescence activity was determined in a luminometer after having added coelenterazine.

[0030] Culture plates giving a positive bioluminescence signal were divided into sectors and a fresh replica plating was carried out. The replica plating was continued until active individual plaques had been identified. In order to subclone the cDNA insertions in the phages in positive plaques [lacuna] took place into the pTriplEX2 vector in E. coli BM25.8 in accordance with the manufacturer's protocol for the SMART cDNA library construction kit. The pTriplEx2 cDNA-transfected E. coli were incubated overnight, at 37° C., in LB medium containing an ampicillin concentration of 100 μg/ml. In order to achieve overexpression, the overnight culture was diluted 1:150 with LB medium and incubated at 37° C. for 1 hour. Induction was then effected by adding IPTG (isopropylthiogalactoside) to a final concentration of 20 mM. The induced culture was incubated at 37° C. for 1 hour and the bacteria were harvested by centrifugation. The cells were disrupted by ultrasonication in 0.5 ml of SM buffer. The chemiluminescence was measured in a luminometer after adding 10 μl of coelenterazine (10⁻⁴ M in methanol).

[0031] Three luciferases which exhibited coelenterazine-dependent luciferase activity were identified. The luciferases were designated Lu164, LuAL and Lu22. The luciferases are described in detail below.

[0032] The invention also relates to functional equivalents of the three luciferases. Functional equivalents are those luciferases which have a comparable substrate spectrum, which are secreted and which are at least 70% homologous. A homology of 80% or 90% is preferred. A homology of 95% is particularly preferred.

[0033] The luciferases are suitable for use as reporter genes for cellular systems, especially for receptors, for ion channels, for transporters, for transcription factors or for inducible systems.

[0034] The luciferases can be used in bacterial systems, for example for titer determination or as substrates for biochemical systems, especially for proteinases.

[0035] The luciferases can also be used as reporter enzymes which are coupled to antibodies or other proteins, e.g. for ELISA, for immunohistochemistry or for Western blotting.

[0036] The luciferases can be used in BRET (Bioluminescence Resonance Energy Transfer) systems.

[0037] The luciferases are also suitable for use as fusion proteins for confocal microscopy or for analyzing protein-protein interactions.

[0038] The luciferases can be used as reporter enzymes which are coupled to biotin, NHS, CN—Br or other coupling mediators, e.g. for ELISA or for immobilization.

[0039] The luciferases can furthermore be used as reporter enzymes which are coupled to DNA or RNA oligonucleotides, e.g. for Northern and Southern blotting or for real time PCR.

[0040] The invention also relates to the purification of the luciferases as wild-type or tag proteins, and to the use of the luciferases in in-vitro translation systems.

[0041] Nucleotide and Amino Acid Sequences

[0042] LuAL

[0043] The luciferase LuAL is a protein having a molecular weight of 23.7 kDa and an isoelectric point of 8.32. The coding nucleotide sequence is: 5′ atggatatgagggttatctttgctcttgttttctcatcattggttca ggccaaatcaactgaattcgatcctaacattaacattgttggtttagaag gaaaatttggtataacaaaccttgagacggatttattcacaatatgggag acaatggatgtcatcaaatcagatattacagatactgatagagtcagcaa ctttgttgcaactgaaaccgatgctaaccgtgggaaaatgcctggcaaaa aactgccactggcagttatcatggaaatggaagccaatgctttcaaagct ggctgcaccaggggatgccttatctgtctttcaaaaataaagtgtacagc caaaatgaaggtgtacattccaggaagatgtcatgattatggtggtgaca agaaaactggacaggcaggaatagttggtgcaattgttgacattcccgaa atctctggatttaaggagatggcacccatggaacagttcattgctcaagt tgatctttgcgctacctgcactactggatgtctcaaaggtcttgccaatg ttaagtgctctgaactcctgaagaaatggctgcctggcagatgtgcaagt tttgctgacaagattcaaaaagaagttcacaatatcaaaggcatggctgg agatcgttga 3′

[0044] which gives rise to the following amino acid sequence: MDMRVIFALVFSSLVQAKSTEFDPNINIVGLEGKFGITNLETDLFTIWET MDVIKSDITDTDRVSNFVATETDANRGKMPGKKLPLAVIMEMEANAFKAG CTRGCLICLSKIKCTAKMKVYIPGRCHDYGGDKKTGQAGIVGAIVDIPEI SGFKEMAPMEQFIAQVDLCATCTTGCLKGLANVKCSELLKKWLPGRCASF ADKIQKEVHNIKGMAGDR

[0045] and the following amino acid composition: Ala: 18 (8.3%) Cys: 10 (4.6%) Asp: 14 (6.4%) Glu: 12 (5.5%) Phe: 10 (4.6%) Gly: 19 (8.7%) His:  2 (0.9%) Ile: 18 (8.3%) Lys: 21 (9.6%) Leu: 15 (6.9%) Met: 10 (4.6%) Asn:  8 (3.7%) Pro:  7 (3.2%) Gln:  5 (2.3%) Arg:  7 (3.2%) Ser:  9 (4.1%) Thr: 15 (6.9%) Val: 14 (6.4%) Trp:  2 (0.9%) Tyr:  2 (0.9%)

[0046] Lu164

[0047] Luciferase Lu164 is a protein having a molecular weight of 23.8 kDa and an isoelectric point of 7.81. The coding nucleotide sequence is: 5′ atggatataaaggttgtctttactcttgttttctcagcattggttca ggcaaaatcaactgaattcgatcctaacattgacattgttggtttagaag gaaaatttggtataacaaaccttgagacggatttattcacaatatgggag acaatggaggtcatgatcaaagcagatattgcagatactgatagagccag caactttgttgcaactgaaaccgatgctaaccgtggaaaaatgcctggca aaaaactgccactggcagttatcatggaaatggaagccaatgctttcaaa gctggctgcaccaggggatgccttatctgtctttcaaaaataaagtgtac agccaaaatgaaggtgtacattccaggaagatgtcatgattatggtggtg acaagaaaactggacaggcaggaatagttggtgcaattgttgacattccc gaaatctctggatttaaggagatggcacccatggaacagttcattgctca agttgaacgttgcgcttcctgcactactggatgtctcaaaggtcttgcca atgttaagtgctctgaactcctgaagaaatggctgcctgacagatgtgca agttttgctgacaagattcaaaaagaagttcacaatatcaaaggcatggc tggagatcgttga 3

[0048] which gives rise to the following amino acid sequence: MDIKVVFTLVFSALVQAKSTEFDPNIDIVGLEGKFGITNLETDLFTIWET MEVMIKADIADTDRASNFVATETDANRGKMPGKKLPLAVIMEMEANAFKA GCTRGCLICLSKIKCTAKMKVYIPGRCHDYGGDKKTGQAGIVGAIVDIPE ISGFKEMAPMEQFIAQVDRCASCTTGCLKGLANVKCSELLKKWLPDRCAS FADKIQKEVHNIKGMAGDR

[0049] and the following amino acid composition: Ala: 21 (9.6%) Cys: 10 (4.6%) Asp: 15 Glu: 13 (6.8%) (5.9%) Phe: 10 (4.6%) Gly: 18 (8.2%) His:  2 Ile: 18 (0.9%) (8.2%) Lys: 22 (10.0%) Leu: 14 (6.4%) Met: 10 Asn:  7 (4.6%) (3.2%) Pro: 7 (3.2%) Gln:  5 (2.3%) Arg:  7 Ser:  8 (3.2%) (3.7%) Thr: 14 (6.4%) Val: 14 (6.4%) Trp:  2 Tyr:  2 (0.9%) (0.9%)

[0050] Lu22

[0051] Luciferase Lu22 is a protein having a molecular weight of 20.2 kDa and an isoelectric point of 7.89. The coding nucleotide sequence is: 5′ atgggagtcaaacttatttttgctgttgtttgtgtcgcagttgccca ggctgccacaattcaggaaaattttgaagacattgatcttgtagccatag gtggcagctttgcatcagatgttgatgctaacagaggtggacatggtgga catcctggcaaaaagatgccaaaagaagtacttatggaaatggaagccaa tgctaaacgagctggctgccacaggggttgtctggtttgtctgtcacaca tcaagtgcacagcacaaatgcagaagtttatcccaggaagatgccatagt tatgcaggagacaaggattctgctcagggaggaattgccggtggtgccat tgttgatatacctgaaattgccggatttaaagaaatgaagcccatggaac agttcattgctcaagttgatctctgtgaagattgcacaactggatgcctc aaaggtcttgccaatgttcattgctctgatctcctgaagaagtggctgcc atcaagatgtaagacatttgcttccaaaattcaatctcaagtggatacca tcaaaggtttggctggagatcgttga 3′

[0052] which gives rise to the following amino acid sequence: MGVKLIFAVVCVAVAQAATIQENFEDIDLVAIGGSFASDVDANRGGHGGH PGKKMPKEVLMEMEANAKRAGCHRGCLVCLSHIKCTAQMQKFIPGRCHSY AGDKDSAQGGIAGGAIVDIPEIAGFKEMKPMEQFIAQVDLCEDCTTGCLK GLANVHCSDLLKKWLPSRCKTFASKIQSQVDTIKGLAGDR

[0053] and the following amino acid composition: Ala: 21 (11.1%) Cys: 11 Asp: 12 Glu:  9 (5.8%) (6.3%) (4.7%) Phe:  7 (3.7%) Gly: 21 His:  6 Ile: 13 (11.1%) (3.2%) (6.8%) Lys: 16 (8.4%) Leu: 12 Met:  7 Asn:  4 (6.3%) (3.7%) (2.1%) Pro:  6 (3.2%) Gln:  9 Arg:  6 Ser:  9 (4.7%) (3.2%) (4.7%) Thr:  6 (3.2%) Val: 13 Trp:  1 Tyr:  1 (6.8%) (0.5%) (0.5%)

[0054] These sequences are also given in the sequence listing.

[0055] Enzymic Activity and Biochemical Characterization of the Luciferases

[0056] The proteins LuAL, Lu164 and Lu22 are enzymes which release light while transforming coelenterazine. They therefore belong to the luciferases. The luciferases can be actively expressed in both bacterial and eukaryotic cells. The luciferases LuA1, Lu164 and Lu22 which are expressed in eukaryotic cells are secreted. No secretion takes place in connection with bacterial expression.

[0057] The activity of the luciferases is temperature-dependent. Temperature optima of 22° C. (for LuAL) and 27° C. (for Lu164) were determined for the luciferases LuAL and Lu164, respectively. The temperature optimum for luciferase Lu22 activity is 4° C. or lower.

EXAMPLES

[0058] Plasmids/Constructs

[0059] The vectors employed for preparing the constructs which are descibed below were the vectors pcDNA3.1(+) and pTriplEx2 from Clontech and the vector pASMplr (in-house construct possessing cAMP-sensitive promoter elements; cre). The derivatives of the vectors were designated pcDNA3-x, pTriplEx2-x and pASM-x.

[0060] LuAL

[0061]FIG. 1 shows the plasmid maps of the vectors pTriplEX2-LuAL, pcDNA3-LuAL and pASM-LuAL

[0062]FIG. 2 shows the plasmid maps of the vectors pTriplEX2-Lu164, pcDNA3-Lu164 and pASM-Lu164

[0063]FIG. 3 shows the plasmid maps of the vectors pTriplEX2-Lu22, pcDNA3-Lu22 and pASM-Lu22

[0064] Coelenterazine Derivates as Substrates of Lu164

[0065] In order to identify substrates for Lu164, 10 μl solutions of different coelenterazine derivatives (10⁻⁴M) were in each case incubated with 10 μl of supernatant from CHO-pcDNA3-Lu164 cell lines and the luminescence was measured. The coelenterazines were obtained from Molecular Probes (USA).

[0066] No differences as compared with luciferase Lu164 were seen in the case of luciferases LuAL and Lu22. Unmodified coelenterazine (Fig. B, coelenterazine a) was identified as being the optimal substrate for Lu164, LuA1 and Lu22.

[0067]FIG. 4 shows coelenterazine derivatives as potential substrates for Lu164 and a graph of the measurement of luminescence for 30 seconds at 8.7 kV in a luminometer (RLU, relative light units); and also a diagram of the molecular structures of the coelenterazine derivatives.

[0068] Enzymic Activity of the Luciferases Lu164, LuAL and Lu22 in Dependence on Coelenterazine

[0069] Bacterial Expression

[0070] The bacterial expression took place in the E. coli strain BL21(DE3) as a result of transforming the bacteria with the expression plasmids pTriplEX2-Lu164, pTriplEX2-LuAL and pTriplEX2-Lu22. The transformed bacteria were incubated at 37° C. for 3 hours in LB medium and expression was induced for 4 hours by adding IPTG to a final concentration of 1 mM. The induced bacteria were harvested by centrifugation, resuspended in PBS and disrupted by ultrasonication. Coelenterazine (10⁻⁴ M in methanol) or luciferin (Firefly Luciferin) was added to 5 μl of the lysate (5 mg/ml) and the chemiluminescence was measured.

[0071] The measurement, in RLU (relative light units), took place at 9.5 kV for 30 seconds. Values of 230 000, 320 000 and 260 000 RLU were measured in the case of Lu164, LuAL and Lu22, respectively. The enzymes were expressed in E. coli BL21(DE3) using the vectors pTriplEx2-Lu164, pTriplEx2-LuAL and pTriplEx2-Lu22.

[0072] Eukaryotic Expression

[0073] Constitutive eukaryotic expression was affected in CHO cells by transfecting the cells with the expression plasmids pcDNA3-Lu164, pcDNA3-LuAL and pcDNA3-Lu22 in transient experiments. For this, 10 000 cells in DMEM-F12 medium were plated, per well, in 96-well microtiter plates and incubated overnight at 37° C. The transfection was effected using the Fugene 6 kit (Roche) in accordance with the manufacturer's instructions. The transfected cells were incubated overnight at 37° C. in DMEM-F12 medium. The chemiluminescence in the medium (5 μl) and the cell lysate (5 μl) was measured for 30 seconds at 9.5 kV in a luminometer, at room temperature, after adding coelenterazine (10⁻⁴ M in methanol).

[0074] Values of 680 000, 670 000 and 510 000 RLU (relative light units) were measured in the case of Lu164, LuAL and Lu22, respectively. The expression was effected in CHO cells using the vectors pcDNA3-Lu164, pcDNA3-LuAL and pcDNA3-Lu22.

[0075] Emission Spectra of the Luciferases Lu164, LuAL and Lu22

[0076] In order to measure the emission spectra, E. coli BL21(DE3) cells were transformed with the plasmids pTriplEx2-Lu164, pTriplEx2-LuAL and pTriplEx2-Lu22 and overexpressed as described under 3.1. 50 μl of coelenterazine (10⁻⁴ M) were added to 100 μl volumes of the bacterial lysates and the emission spectra were measured. Graphs of the emission spectra of the luciferases are shown below.

[0077] In the case of the luciferases LuAL, Lu164 and Lu22, maximum emission resulting from the substrate transformation takes place at a wavelength of about 490 nm.

[0078]FIG. 5 shows the emission spectra of the luciferases Lu164 (A), LuAL (B) and Lu22 (C) following bacterial expression (RLU, relative light units)

[0079] Secretion of the Luciferases Lu164, LuAL and Lu22 from CHO Cells, Taking as Examples Lu164 and LuAL

[0080] In order to characterize the expression of the luciferases LuAL, Lu164 and Lu22 in eukaryotic cells, CHO cells were stably transfected with the plasmids pcDNA3-LuA1, pcDNA3-Lu164, pcDNA3-Fireluc and pcDNA3.1(+). The resulting clones were cultured in DMEM-F12 medium. Firefly luciferase was used as a positive control for nonsecreted luciferase. The plasmid pcDNA3.1(+) was used as a control plasmid for detecting potential endogenous activity in the CHO parent cell.

[0081] In order to detect the secretion of the luciferases, 2000 cells were plated on 384-well microtiter plates. After 24 hours, the medium was removed and the cells were washed with Tyrode solution and 30 μl of fresh medium were added. The first measurement (0 h) then took place, in a luminometer at 9.5 kV for 30 seconds, after adding 5 μl of coelenterazine (10⁻⁴ M) or luciferin in the case of the Firefly luciferase. The 1 h to 5 h measurements took place after one to five hours.

[0082]FIG. 6 depicts the increase in luciferase activity in the medium in dependence on the time. The Firefly luciferase was not secreted. The luciferases LuAL, Lu164 and Lu22 are secretory luciferases.

[0083]FIG. 6 shows the luciferase activity in the CHO cell medium (5 μl) after the CHO cells have been transfected with pcDNA3-LuAL, pcDNA3-Firefly, pcDNA3-Lu164 or pcDNA3 as the control vector without any cDNA insertion. (RLU, relative light units; h, hours; Firefly: Firefly luciferase)

[0084] Dependence of the Luciferase Activity on the Temperature

[0085] In order to determine the temperature dependence of the luciferases Lu22, Lu164 and LuAL, CHO cells were transiently transfected with the vectors pcDNA3-Lu22, pcDNA3-Lu164 and pcDNA3-LuA1 and the luciferase activity in the supernatants was determined at temperatures of between 0 and 47° C. In order to do this, the cell supernatant and the coelenterazine solution were adapted to the measurement temperature for 5 minutes. The measurement took place at 9.5 kV for 30 seconds in a luminometer.

[0086]FIG. 7 shows the luminescence which was measured, in dependence on the temperature, in the case of the luciferases LuA1, Lu164 and Lu22. The temperature optimum for the luciferase activity of LuAL is 27° C. A temperature optimum of 22° C. and of 4° C. or lower was determined in the case of Lu164 and Lu22, respectively.

[0087]FIG. 7 shows the temperature-dependent luciferase activity in CHO cell medium (5 μl) following transfection with pcDNA3-LuAL, pcDNA3-Firefly and pcDNA3-Lu164. (RLU: relative light units; medium: DMEM-F12+10% FCS)

[0088] Induced Expression of the Luciferases Lu164, LuAL and Lu22 in CHO Cells Taking as an Example LuAL

[0089] Eukaryotic expression was induced in CHO cells by transfecting the cells with the expression plasmid pASM-LuAL in transient experiments. For this, 10 000 cells in DMEM-F12 medium were plated per well in 96-well microtiter plates and incubated overnight at 37° C. The transfection was effected using the Fugene 6 kit (Roche) in accordance with the manufacturer's instructions. The transfected cells were incubated overnight, at 37° C., in DMEM-F12 medium. They were then induced with Forkolin (10⁻⁵ M) for 5 hours. The chemiluminescence in the medium and in the cell lysate was then measured, at 9.5 kV for 30 seconds, in a luminometer after having added coelenterazine (10⁻⁴ M in methanol).

[0090]FIG. 8 shows the induced expression of LuAL in CHO cells. The expression was induced for 5 hours with Forskolin (10⁻⁵ M) at 37° C. The activity was measured in 10 μl of cell supernatant (RLU: relative light units; induction factor: ratio of induced RLU to uninduced RLU)

[0091] Use of the Luciferases Lu164, LuAL and Lu22 as Reporter Genes in Cellular Systems Taking as Examples the Receptors NPY2 and A2A and using LuAL as the Reporter Gene

[0092] In order to be able to analyze the activation of G protein-coupled receptors by receptor-specific ligand in cell-based systems, the cDNA sequence for luciferase LuAL was cloned into the expression vector pASMplr. The expression vector pASMplr contains cAMP-sensitive promoter elements (CRE) which enable the intracellular concentration of cAMP to be measured indirectly. The luciferase serves as the reporter gene in the system.

[0093] The use of the luciferases Lu22, Lu164 and Lu22 as reporter genes in cellular systems was demonstrated by taking as an example the G protein-coupled receptors NPY2 (neuropeptide receptor 2) and A2A (adenosine receptor 2a). To do this, the stable clone CHO-pASM-LuAL was transiently transfected with the vector pcDNA3-NPY2 or the vector pcDNA3-A2A. The receptor NPY2 is a Gi-coupled receptor, while the A2A receptor is a Gs-coupled receptor.

[0094] The A2A receptor was activated for 4 h by adding 1 μM NECA. The NPY2 receptor was activated by adding 10 μM NPY2 peptide in the presence of 10⁻⁵ M Forskolin. The luciferase activity in the medium (30 μl) was measured, at 9.5 kV and for 30 seconds in a luminometer, after having added coelenterazine (10⁻⁴ M).

[0095]FIG. 9 shows the use of the luciferases as reporter genes for cellular systems taking as an example the G protein-coupled receptors A2A and NPY2. (RLU: relative light units)

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1 6 1 657 DNA Metridia longa 1 atggatatga gggttatctt tgctcttgtt ttctcatcat tggttcaggc caaatcaact 60 gaattcgatc ctaacattaa cattgttggt ttagaaggaa aatttggtat aacaaacctt 120 gagacggatt tattcacaat atgggagaca atggatgtca tcaaatcaga tattacagat 180 actgatagag tcagcaactt tgttgcaact gaaaccgatg ctaaccgtgg gaaaatgcct 240 ggcaaaaaac tgccactggc agttatcatg gaaatggaag ccaatgcttt caaagctggc 300 tgcaccaggg gatgccttat ctgtctttca aaaataaagt gtacagccaa aatgaaggtg 360 tacattccag gaagatgtca tgattatggt ggtgacaaga aaactggaca ggcaggaata 420 gttggtgcaa ttgttgacat tcccgaaatc tctggattta aggagatggc acccatggaa 480 cagttcattg ctcaagttga tctttgcgct acctgcacta ctggatgtct caaaggtctt 540 gccaatgtta agtgctctga actcctgaag aaatggctgc ctggcagatg tgcaagtttt 600 gctgacaaga ttcaaaaaga agttcacaat atcaaaggca tggctggaga tcgttga 657 2 218 PRT Metridia longa 2 Met Asp Met Arg Val Ile Phe Ala Leu Val Phe Ser Ser Leu Val Gln 1 5 10 15 Ala Lys Ser Thr Glu Phe Asp Pro Asn Ile Asn Ile Val Gly Leu Glu 20 25 30 Gly Lys Phe Gly Ile Thr Asn Leu Glu Thr Asp Leu Phe Thr Ile Trp 35 40 45 Glu Thr Met Asp Val Ile Lys Ser Asp Ile Thr Asp Thr Asp Arg Val 50 55 60 Ser Asn Phe Val Ala Thr Glu Thr Asp Ala Asn Arg Gly Lys Met Pro 65 70 75 80 Gly Lys Lys Leu Pro Leu Ala Val Ile Met Glu Met Glu Ala Asn Ala 85 90 95 Phe Lys Ala Gly Cys Thr Arg Gly Cys Leu Ile Cys Leu Ser Lys Ile 100 105 110 Lys Cys Thr Ala Lys Met Lys Val Tyr Ile Pro Gly Arg Cys His Asp 115 120 125 Tyr Gly Gly Asp Lys Lys Thr Gly Gln Ala Gly Ile Val Gly Ala Ile 130 135 140 Val Asp Ile Pro Glu Ile Ser Gly Phe Lys Glu Met Ala Pro Met Glu 145 150 155 160 Gln Phe Ile Ala Gln Val Asp Leu Cys Ala Thr Cys Thr Thr Gly Cys 165 170 175 Leu Lys Gly Leu Ala Asn Val Lys Cys Ser Glu Leu Leu Lys Lys Trp 180 185 190 Leu Pro Gly Arg Cys Ala Ser Phe Ala Asp Lys Ile Gln Lys Glu Val 195 200 205 His Asn Ile Lys Gly Met Ala Gly Asp Arg 210 215 3 660 DNA Metridia longa 3 atggatataa aggttgtctt tactcttgtt ttctcagcat tggttcaggc aaaatcaact 60 gaattcgatc ctaacattga cattgttggt ttagaaggaa aatttggtat aacaaacctt 120 gagacggatt tattcacaat atgggagaca atggaggtca tgatcaaagc agatattgca 180 gatactgata gagccagcaa ctttgttgca actgaaaccg atgctaaccg tggaaaaatg 240 cctggcaaaa aactgccact ggcagttatc atggaaatgg aagccaatgc tttcaaagct 300 ggctgcacca ggggatgcct tatctgtctt tcaaaaataa agtgtacagc caaaatgaag 360 gtgtacattc caggaagatg tcatgattat ggtggtgaca agaaaactgg acaggcagga 420 atagttggtg caattgttga cattcccgaa atctctggat ttaaggagat ggcacccatg 480 gaacagttca ttgctcaagt tgaacgttgc gcttcctgca ctactggatg tctcaaaggt 540 cttgccaatg ttaagtgctc tgaactcctg aagaaatggc tgcctgacag atgtgcaagt 600 tttgctgaca agattcaaaa agaagttcac aatatcaaag gcatggctgg agatcgttga 660 4 219 PRT Metridia longa 4 Met Asp Ile Lys Val Val Phe Thr Leu Val Phe Ser Ala Leu Val Gln 1 5 10 15 Ala Lys Ser Thr Glu Phe Asp Pro Asn Ile Asp Ile Val Gly Leu Glu 20 25 30 Gly Lys Phe Gly Ile Thr Asn Leu Glu Thr Asp Leu Phe Thr Ile Trp 35 40 45 Glu Thr Met Glu Val Met Ile Lys Ala Asp Ile Ala Asp Thr Asp Arg 50 55 60 Ala Ser Asn Phe Val Ala Thr Glu Thr Asp Ala Asn Arg Gly Lys Met 65 70 75 80 Pro Gly Lys Lys Leu Pro Leu Ala Val Ile Met Glu Met Glu Ala Asn 85 90 95 Ala Phe Lys Ala Gly Cys Thr Arg Gly Cys Leu Ile Cys Leu Ser Lys 100 105 110 Ile Lys Cys Thr Ala Lys Met Lys Val Tyr Ile Pro Gly Arg Cys His 115 120 125 Asp Tyr Gly Gly Asp Lys Lys Thr Gly Gln Ala Gly Ile Val Gly Ala 130 135 140 Ile Val Asp Ile Pro Glu Ile Ser Gly Phe Lys Glu Met Ala Pro Met 145 150 155 160 Glu Gln Phe Ile Ala Gln Val Asp Arg Cys Ala Ser Cys Thr Thr Gly 165 170 175 Cys Leu Lys Gly Leu Ala Asn Val Lys Cys Ser Glu Leu Leu Lys Lys 180 185 190 Trp Leu Pro Asp Arg Cys Ala Ser Phe Ala Asp Lys Ile Gln Lys Glu 195 200 205 Val His Asn Ile Lys Gly Met Ala Gly Asp Arg 210 215 5 573 DNA Metridia longa 5 atgggagtca aacttatttt tgctgttgtt tgtgtcgcag ttgcccaggc tgccacaatt 60 caggaaaatt ttgaagacat tgatcttgta gccataggtg gcagctttgc atcagatgtt 120 gatgctaaca gaggtggaca tggtggacat cctggcaaaa agatgccaaa agaagtactt 180 atggaaatgg aagccaatgc taaacgagct ggctgccaca ggggttgtct ggtttgtctg 240 tcacacatca agtgcacagc acaaatgcag aagtttatcc caggaagatg ccatagttat 300 gcaggagaca aggattctgc tcagggagga attgccggtg gtgccattgt tgatatacct 360 gaaattgccg gatttaaaga aatgaagccc atggaacagt tcattgctca agttgatctc 420 tgtgaagatt gcacaactgg atgcctcaaa ggtcttgcca atgttcattg ctctgatctc 480 ctgaagaagt ggctgccatc aagatgtaag acatttgctt ccaaaattca atctcaagtg 540 gataccatca aaggtttggc tggagatcgt tga 573 6 190 PRT Metridia longa 6 Met Gly Val Lys Leu Ile Phe Ala Val Val Cys Val Ala Val Ala Gln 1 5 10 15 Ala Ala Thr Ile Gln Glu Asn Phe Glu Asp Ile Asp Leu Val Ala Ile 20 25 30 Gly Gly Ser Phe Ala Ser Asp Val Asp Ala Asn Arg Gly Gly His Gly 35 40 45 Gly His Pro Gly Lys Lys Met Pro Lys Glu Val Leu Met Glu Met Glu 50 55 60 Ala Asn Ala Lys Arg Ala Gly Cys His Arg Gly Cys Leu Val Cys Leu 65 70 75 80 Ser His Ile Lys Cys Thr Ala Gln Met Gln Lys Phe Ile Pro Gly Arg 85 90 95 Cys His Ser Tyr Ala Gly Asp Lys Asp Ser Ala Gln Gly Gly Ile Ala 100 105 110 Gly Gly Ala Ile Val Asp Ile Pro Glu Ile Ala Gly Phe Lys Glu Met 115 120 125 Lys Pro Met Glu Gln Phe Ile Ala Gln Val Asp Leu Cys Glu Asp Cys 130 135 140 Thr Thr Gly Cys Leu Lys Gly Leu Ala Asn Val His Cys Ser Asp Leu 145 150 155 160 Leu Lys Lys Trp Leu Pro Ser Arg Cys Lys Thr Phe Ala Ser Lys Ile 165 170 175 Gln Ser Gln Val Asp Thr Ile Lys Gly Leu Ala Gly Asp Arg 180 185 190 

1. A DNA or RNA molecule having the sequence for the luciferase LuAL, Lu164, Lu16, Lu39, Lu45, Lu52 or Lu22 or a functional equivalent thereof.
 2. A molecule as claimed in claim 1, in which the sequence contains a functional promoter located 5′ to the sequence.
 3. A molecule as claimed in claim 2 which is a component of a recombinant DNA or RNA vector.
 4. An organism which harbors a vector as described in claim
 3. 5. An oligonucleotide which contains more than 10 consecutive nucleotides which are identical or complementary to the DNA or RNA sequence.
 6. A peptide which is encoded by a nucleotide sequence as claimed in claim
 1. 7. A peptide which contains more than 5 consecutive amino acids which are immunologically recognized by antibodies directed against Lu164, LuAL or Lu22.
 8. The use of the luciferases as claimed in claims 1 to 6 as reporter genes for cellular systems. 